DADU setbacks, height and lot coverage
There is no single setback or height number for every Eastside DADU. Start with the parcel’s jurisdiction, zone and building configuration, then check environmental and access constraints.
Sources checked November 5, 2026. Confirm the requirements for your parcel with its permitting authority.
Treat each measurement as a separate question
A setback concerns the distance to a property line. Building height controls the vertical envelope. Lot coverage and impervious-surface limits concern how much of the property is occupied or covered. Satisfying one of these measurements does not establish that the others work.
Ask which surfaces and building features count in each calculation. Roof projections, covered areas and the method used to measure grade can matter to a design. Record the rule and the drawing it affects rather than relying on a single sketch labeled “fits.”
Know what Washington’s ADU law changes
RCW 36.70A.681 limits local ADU regulation. It restricts imposing ADU setbacks and certain other design controls that are more restrictive than those for principal homes. It also addresses maximum floor-area limits, roof-height limits and siting at a public-alley lot line.
The statute’s height provision includes an exception where the principal unit has a height limit below 24 feet. It also excludes certain critical-area and watershed lots from the section. Read the applicable provisions with the local authority rather than treating a state minimum standard as approval for a particular building.
Official guidance: RCW 36.70A.681: limits on local ADU regulation.
Compare the building configurations
A freestanding cottage, a home above a detached garage and a building beside a public alley may need different siting analysis. Start with the form of building you actually want and ask which development standards apply to that form.
A useful example is Sammamish: the city publishes different dimensional tables for a detached ADU that stands alone and an ADU attached to another structure. The dedicated Sammamish guide explains that distinction. Do not transfer either table to a different city.
Test the whole site
Draw the property boundary, required yards, existing buildings, known easements and the proposed building footprint on one plan. Then add the access and utility work needed to build and maintain it. A layout that only works before these items are drawn still needs refinement.
Before choosing a two-story design, compare privacy, stair use, room arrangement and the relationship to the main house. A compact footprint can help preserve yard space, but the best option is the one that fits the site and the people who will live there.
A few things to know
Is a five-foot setback standard everywhere?
No. Confirm the applicable zone, street frontage, building type and site constraints with the permitting authority.
Does being under the height limit mean my design is approved?
No. Height is one part of review alongside floor area, setbacks, coverage, access, utilities and other applicable requirements.
Keep planning
Sammamish DADU Setbacks: Cottage or Garage ADU?
Compare Sammamish’s freestanding and garage-related ADU setback tables, front yards, height and size before drawing your DADU.
Duvall DADU Permits: What You Need to Know
Duvall DADU permits explained: where to apply, the recorded ADU notice, zoning checks and the documents to prepare for a backyard cottage.
Can I Build a DADU on the Eastside? Start With Your City
Find the DADU rules for Duvall, Woodinville, Redmond, Bothell and six other Eastside communities, with local permit and eligibility guides.